Flat panel displays have been widely used in various products and fields in recent years, and the flat panel displays are required to have a larger size, a higher definition, and lower power consumption.
In this situation, organic EL display devices, which include organic EL elements utilizing electroluminescence of organic materials, draw great attention as flat panel displays that are of solid state and are excellent in terms of low-voltage driving, rapid response, and self-luminousness.
The organic EL display devices each include a substrate for an organic EL display device, and the substrate includes, for example, thin film transistors (hereinafter, also abbreviated as TFTs) and organic EL elements connected to the TFTs on an insulating substrate such as a glass substrate. The organic EL elements each have a stacked structure of a first electrode, an organic EL layer, and a second electrode in the given order. The first electrode is connected to the corresponding TFT. The organic EL layer has a stacked structure of layers, such as a hole-injection layer, a hole-transport layer, an electron-blocking layer, a light-emitting layer, a hole-blocking layer, an electron-transport layer, an electron-injection layer.
With regard to organic EL elements, organic materials for forming organic EL layers usually have low water resistance and are not suitable for wet processes. Thus, organic EL layers are generally formed by vacuum vapor deposition utilizing a vacuum thin-film-forming technique. Therefore, a vapor deposition device including a vapor deposition source in a vacuum chamber is widely used in production of an organic EL element including a step of forming an organic layer.
In addition, scanning vapor deposition devices have been developed recently which perform vapor deposition on a substrate through a mask whose area is smaller than that of the substrate while moving the substrate in one direction relative to the vapor deposition source, thereby forming a film-forming pattern.
Specifically, for example, a vapor deposition device is disclosed which performs vapor deposition through multiple opening patterns of a vapor deposition mask while transporting a substrate in the X direction to form a thin-film pattern, wherein the vapor deposition mask includes an alignment mark formed by providing an opening having a certain shape in an edge region on at least one end side in the Y direction crossing the X direction. This vapor deposition device includes an image-sensing means which includes multiple light-receiving elements arranged in a straight line in the Y direction and which is configured to photograph simultaneously both the alignment mark of the vapor deposition mask and a thin-line follow-up mark provided in an edge region of the substrate on at least one end side in the Y direction correspondingly to the alignment mark and parallel to the X direction to allow detection of the positional relationship between the marks; and an alignment means configured to move the substrate and the vapor deposition mask relatively in the XY plane based on the positional relationship between the marks photographed and detected by the image-sensing means, continually during transportation of the substrate, to correct misalignment between the substrate and the vapor deposition mask (for example, see Patent Literature 1).